This invention relates to liquid metal cooled nuclear reactor constructions.
In one kind of construction of liquid metal cooled nuclear reactor generally known as of the pool kind, the reactor core, heat exchangers and coolant circulating pumps are submerged in a pool of liquid metal coolant. In operation of the nuclear reactor it is necessary to be able to locate and identify components submerged in the pool and before moving rotating shields in the roof of the pool containing vault it is necessary to ensure that all the normally suspended absorber rods have been inserted in the core and released from their suspensions. Television cameras are unsuitable for use in the opaque liquid metal but ultrasound in the mega hertz range has been used to give a television screen kind of display. There is some difficulty in transmitting ultrasound signals from a transducer into the pool of coolant because the transducer must be protected from the high temperature environment of the reactor coolant but this difficulty has been partially overcome by transmitting the signals by way of a wave guide extending from the transducer into the pool of coolant. Such a wave guide may comprise a column of liquid metal within a dip tube. However, in order to support the column of liquid metal in the dip tube and to isolate it from the liquid metal of the pool a diaphragm has been used but the diaphragm causes unwanted attenuation of the transmitted signals.
An object of the invention is to provide a liquid metal cooled nuclear reactor construction having means for transmitting ultrasonic signals into and from a pool of reactor coolant by way of a liquid wave guide comprising a column of reactor coolant which is uninterrupted by a diaphragm.